1. Field of the Invention
The present invention relates generally to substrate inspection and more particularly, to systems and methods for inspecting substrates.
2. Description of the Related Art
The semiconductor chip fabrication process requires numerous operations and sub-processes. Examples of such a fabrication operations include etching, chemical mechanical polishing (CMP), deposition, rinsing, drying and other operations. Each of the manufacturing operations must be monitored to make sure that the operation is completed accurately, repeatably and in a timely manner.
Many types of manufacturing processes (e.g., etch, rinse, dry, deposition) must also have some sort of subsystem or sub-process capable of monitoring the progress of the respective manufacturing process. This is increasingly important as process control requirements become ever more stringent as device feature sizes become ever smaller and as the level of integration increases. Typically, the monitoring system or sub-process is separate from the manufacturing process. By way of example, in a wet chemical etch manufacturing process, the wet etch process is typically interrupted and the progress is evaluated as follows. The etch process is applied to the semiconductor substrate for an initial period. The semiconductor substrate is then rinsed, dried and removed from the etch process tool to be evaluated using metrology from an appropriate subsystem or sub-process to determine if the wet etch process has reached the desired goal. If the etch process has reached the desired goal (i.e., if the etch process has etched away the desired material) then a subsequent process(es) (e.g., clean, rinse, dry) is applied to the semiconductor substrate.
Alternatively, if the wet etch process has not attained the desired goal (i.e., if the etch process has not removed all of the desired material) then the etch process is applied to the semiconductor substrate again in a rework process. After one or more iterations of the rework process, the wet etch process will remove the desired material from the semiconductor substrate. In the case of a batch processing system, a single semiconductor substrate may be used to verify the rework process required (e.g., to correct process time) before reworking the entire batch of substrates. In the case of a single semiconductor substrate processing system, a similar method could be used before committing an entire lot of substrates for rework wet etch processing.
Another examples include cleaning and rinsing processes that use fluids (i.e., wet cleaning processes). The wet cleaning processes can leave fluid droplets on the surface being cleaned. The wet cleaning process can also leave particle contaminants on the surface being cleaned. Such droplets and particles can interfere with subsequent processes. As described above, typical process monitoring is conducted in a separate inspection system. This separate inspection system requires additional handling and processing that negatively impacts throughput and increases the possibility for handling errors and damage.
In view of the foregoing, what is needed is an in-situ system and method for examining a surface to identify fluid droplets and particles on the surface after a wet cleaning process.